1. Field
Example embodiments of the inventive concepts relate to an image sensor and a method of fabricating the same.
2. Description of the Related Art
Image sensors convert an optical image into an electrical signal. With recent advancements in computer and communication industries, the demands for image sensors with enhanced performance are increasing in various fields such as digital cameras, camcorders, personal communication systems, game devices, security cameras, micro-cameras for medical use, and robots.
Metal oxide semiconductor (MOS) image sensors can be driven using a simple driving method and can be implemented using various scanning methods. In MOS image sensors, signal-processing circuits can be integrated onto a single chip. Thus, the size of a product including such a MOS image sensor can be reduced. In addition, since MOS image sensors are compatible with MOS processing technology, manufacturing costs can be reduced. Due to their low power consumption, MOS image sensors can be applied in products with limited battery capacity. That is, technological development accompanied by achievement of high resolution is sharply increasing the use of MOS image sensors.
A MOS image sensor includes photoelectric conversion elements, which sense the amount of incident light, and a plurality of metal wiring layers which output an optical signal stored in each of the photoelectric conversion elements. In this case, however, incident light may be reflected by the metal wiring layers or absorbed by an interlayer insulating film, thereby reducing sensitivity. In addition, the reflected light may be absorbed by adjacent pixels, thereby causing crosstalk.
In this regard, an image sensor having a structure, in which a backside of a substrate is ground and light is incident from the backside of the substrate, has been suggested. Such an image sensor is called a backside illuminated (BI) image sensor. In a BI image sensor, metal wiring layers are not formed on a backside of a substrate upon which light is incident. Therefore, incident light is not reflected by the metal wiring layers or absorbed by an interlayer insulating film.